Russian knapweed (Centaurea repel) or (Acroptilon repens) Chemical Control
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Desription of Plant:
The stems are erect and branched openly, they can be from 18 to 36 inches tall. Lower leaves are 2 to 4 inches long and the upper leaves are very narrow. The stems can also be ridged and stiff and branched, the younger stems are covered with the soft gray hairs, the upper leaves are small also, leaves that are at the middle of the stem have toothed margins. The flowers are cone-shaped and the heads are 1/4 to ½ inches in diameter. They are solitary at the tip of the stem, the ray flowers are pink to lavender, they can be un-shaded, when they mature the color becomes a straw color in the fall, they are borne on branch tips during the summer and the fall. Flowering occurs from June toAugust. The flowers have a thistle like texture, are 1/3 to 1/4" in diameter and are lavender to white in color. The seeds are flattened, ivory color, 2-3 mm long, 2 mm broad, 1 mm thick, and have small bristles. The bristles of the seeds are white.
Useful Herbicides:
The useful Herbicides are Tordon, Curtail, and Transline. The way you put all these on is to Broadcast.
Herbicide Brand How to Apply When to Apply Comments Tordon Broadcast Before Full Flower Or Fall Regrowth none Curtail Broadcast Before Full Flower Or Fall Regrowth none Transline Broadcast Before Full Flower Or Fall Regrowth none
Further Information About These Herbicides:
Herbicide Brand Active Ingredient Mode of Action Comments Tordon Picloram acid present as a potassium salt Growth Regulator Herbicide Controls deep rooted perenial weeds Curtail Clopyralid and Ester formulated as an emulsifiable Growth Regulator Herbicide Do not apply to weeds stressed longer than 20 day Transline " " "
Soucres:
1. Hall, Linda, How Herbicides Work Mechanisms of Action, July 1996, Alberta Ag, Food and Rurual Development, Publishing Branch, ISBN0-7732-6131-1.
2. Saskatchewan Agriculture and Food, Extension Service, Guide to Crop Protection 2002, Weeds, Plant Diseases, Insects. Regina Rural Service Centre Room 101, 3085 Alberta Street REGINA SK S4S 0B1.
3. Dewey, S.A, Whitson, T.D, Sheley, Roger, Weed Management Handbook, 1997-1998.
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By Drew Malchi 5/29/02 Updated by: Candace Webb 5/13/03
Candace